Silk improved in weight, durability, and appearance and process for obtaining the same



Patented May 17, 1932 FRIEDRICH W. WEBER, OF HACKENSAOK, NEW JERSEY,ASSIGNOR T MAY'WOOD CHEMICAL WORKS, 015 HAYWOOD, NEW JERSEY, AGORPOBATION OF NEW JERSEY SILK HEPROVED IN WEIGHT, DURABILI'IY, ANDAPPEARANCE AND PROCESS FQR OBTAINING THE SAME No Drawing.

This invention relates to silk improved in Weight, durability andappearance, the obj ect of the invention being to provide a process bywhich said improved product can be obtained with great regularity,greater convenience and at a lower price.

In the many efforts to substitute, on account of its high price and itsharmful action, the tin-tetrachloride for the treatment of silk toincrease its weight, a great number of chemicals have been suggestedwith more or less success. Among these chemicals tried to substitute thetin tetrachloride are especially the salts of the rare earth metalswhich, owing to their high atomic Weight were expected to giveespecially good results. The finished product obtained by treating silkwith solutions of such rare earth metals were highly promising as aconsiderable increase in weight could relatively easily be obtainedthough otherwise the quality of the fiber was not up to therequirements. Not-' withstanding some efforts in this line properprogress has not'been accomplished and the failure of the rare earthmetals was usually attributed to the readiness with which for instancethe cerous compounds, contained in the applied rare earth metals, changeto the ceri-compounds and that thereby changes in the silk fiber arecaused which detract very much from the obtained result.

Though there are processes in which the tin tetrachloride is at leastpartly substituted by the salts of certain other metal salts, all theseprocesses applying either salts of the rare earth metals exclusively orapplying the same in the presence of other metals salts, for instancethose of tin, have not been able to get a foothold in the U. S. silkindustry notwithstanding the fact that the highly developed industry ofthe rare earth metals would have been able to furnish all necessarysalts of these metals in the greatest quantities and purity.

Long years of experience in the application of the rare earth metalcompounds have convinced me that in fact the salts of the rare earthmetal compounds, especially if they contain cerium, exert a deleteriousefiect on the silk fiber and therefore should never Application filed.February 2, 1927. Serial No. 165,504.

be applied directly to the silk fiber because the original strength andelasticity is much affected by them, even if the lustre of the silkshould not suffer, and that in this manner an industrial product willnever be obtained. This efiect of the salts of the rare earth metals,especially in the presence of cerium, is so pronounced that even theiruse in the presence of varying quantities of other metal salts will notremedy the situation; the reason for this appears to be that this doesnot avoid the direct contact of the silk fiber by the cerium compound.

I have now found out that owing to the otherwise undesirable effect ofthe ocrium compounds on the silk the same must always first be given aprotective coat before the treatment of silk with rare earth metalcompounds can take place. This protective coat is generated by firsttreating the silk fiber with the solution of a tin salt, for instancesuch as tin tetrachloride. The recognition of the necessity of thusfirst preparing the silk for its further treatment with the salts of therare earth metals is important for the facts stated further below. Ofthe solutions of the salts of the rare earth metals I found that of theacetates the most suitable, especially. that carrying a content of 810%of oxides of the rare earth metals with the exception, or at least onlya small content of thorium.

phosphate is entirely avoided because the same is enveloped by the tinphosphate as will be more clearly seen from the description below of oneway of operating my invention.

To carry the same into effect, I can for instance proceed as follows: Askein of silk, degummed in any of the usual Ways and Moreover, the well'10 at a temperature of approximately 70 25 the rare earth metals.

weighing about 45 grams, is immersed for about one hour into a 50% tintetrachloride solution which was diluted by a like volume of water. Thesilk is then taken out of the 5 bath, the adhering tin chloride solutionis pressed out and the silk is then well washed with water. Thereuponthe silk thus treated is immersed into a slightly agitated bath of a610% disodium phosphate solution ke t This treatment is also continuedfor about one hour, the silk is then taken out and the solution squeezedout of it and then the silk is well washed with water. The treatmentwith tin tetrachloride is once'more repeated in exactly the same way asdescribed above and followed by another treatment with disodiumphosphate solution. Now I treat the silk with the solution of a salt ofthe rare earth metals. The well washed and almost dry silk fiber is nowimmersed for approximately one hour into a solution of the acetates ofthe rare earth metals, free of thorium, containing approximately -810%of oxides of The silk is then taken out of the bath, squeezed to removethe adhering solution, and well washed, whereupon the silk is .thenimmersed in an 840% solution of disodium phosphate, for one hour, isthen taken out and squeezedto remove the adhering solution and is thenwell Washed with water. This operation of treating the silk with asolution of the acetates of the rare earth metals and then with asolution of sodium di-phosphate is repeated three times more. Thishaving been done the silk thus treated is returned once more to the tintetrachloride bath for one hour, freed of the adhering tin tetrachloridesolution and washed with water and finally treated again in a disodiumphosphate bath, freed of the adhering solution and well washed withwater.

The silk treated by my new process can be soaped, dyed and finished inany of the well known ways.

The skein of silk, after having been treated as above, increased inweight from grams to 108 grams; it contains approximately evenquantities of tin phosphate and of the phos 0 phates of the applied rareearth metals and shows an excellent lustre and perfect whiteness,undiminished elasticity and strength. It is noteworthy that its fiber,when tested under the microscope, showed an absolute eveness in thethickness of the fiber.

I may furthermore say that if desired, the weighting of the silk withthe rare earth metal compounds can be operated more than four times asdescribed above without any detriment to the desired and requiredproperties of the fiber. I may also say that for the purposes of theinvention also other solutions of the salts of the rear earth metals maybe used, such as chlorides of the same, but owing to the liberation ofmineral acids, dur- .ing the process I prefer the acetates of the rareearth metals which should be free of showing a dull appearance werealways due to the presenceof more or less greater quantities of thoriumwhereas this trouble .is avoided by the presence of minor quantities ofthe same as then the effect of the compounds of the rare earth metalskeeps down this influence of thorium.

In regard to the chemical side of the process I may furthermore say thatthe above mentioned fixing bath of disodium hosphate may be substitutedby sodium si icate or by that of any other chemical forming an insolublesalt with any of the metal salts coming in consideration for my newprocess. I may say that in the repeated application of such fixing bathsI may also use for instance alternately another fixing bath, forinstance one of a solution of disodium phosphate and of sodium silicate.

In mentioning degummed silk in the above example, I may say that theprocess can also be operated with or applied to raw silk, and silkfabric as well as to silk in the skein. It is thus evident that variouschanges can be made in the operation of my new process without deviatingfrom the spirit of or sacrificing the advantages of the invention assuch changes fall within the scope of the ap pended claims in which suchintermediate steps, as for instance removing the solution adhering tothe silk by squeezing and washing then the silk with water beforebringing it into the next treating bath, represent steps which are anatural accessory to each preceding step before one can accede to thenext following one.

What I claim is:

1. The process of improving silk, comprising treating silk first with asolution of a tin salt, subjecting the silk thus treated to a solutionof disodium phosphate, immersmg the thus treated silk into a solution ofa saltof the rare earth metals free of thorium, subjecting then the silkto a solution of disodium phosphate, returning the silk to the solutionof the tin salt, and finally subjecting it again to the solution of thedisodium phosphate.

' 2. The process of improving silk, comprising treating silk first witha solution of tin tetrachloride, subjecting the silk thus treated to asolution of disodium phosphate, immersing the thus treated silk into asolution of the acetate of the rare earth metals free of thorium,subjectingthen the silk to a solution of disodium phosphate, returningthe silk to the solution of tin tetrachloride, and finally subjecting itagain to the solution of disodium phosphate.

3. The process of improving silk with the salts of the rare earthmetals, comprising treating first the silk with a solution of tintetrachloride, then with a solution of disodium phosphate, and then witha solutionfof an acetate of a rare earth metal free of tliorium.

m 4. As a new article of manufacture, silk loaded with approximatelyequal amounts of an insoluble salt of tin and of a compound of a rareearth metal other than thorium, in

' layers deposited alternately upon each other the first layerconsisting of the tin salt.

5. The process of Weighting silk which comprises treating the silk fiberwith a solu tion of a tin compound and treating the same with a solublephosphate, then treating the fiber with a solution of a salt of a rareearth metal, and again treating the fiber with a soluble phosphate.

6. The process of weighting silk which comprises treating the silk fiberwith a solution of a tin compound and treating the same with a solublephosphate, then'treating the fiber with a solution of a salt of acerium, and again treating the fiber with a soluble phosphate.

7 The process of weighting silk which comprises treating the silk fiberwith a solution of a tin compound and treating the same with a solublephosphate, then treating the fiber with a solution of cerium acetate,and

0 again treating the fiber with a soluble phosphate.

I In witness whereof I have hereunto set my hand this 31st day ofJanuary, 1927.

m FRIEDRICH W. BER.

